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Direct organocatalytic Mannich-type reactions of thioesters provide for the expedient and diastereoselective synthesis of protected beta-amino acids. A variety of thioesters were found to be reactive with different imines under mild conditions to provide beta-amino acids in good yields. This chemistry was extended to a diastereo- and enantioselective variant.

The development of enantioselective anti-selective Mannich-type reactions of aldehydes and ketones with imines catalyzed by 3-pyrrolidinecarboxylic acid and related pyrrolidine derivatives is reported in detail. Both (3R,5R)-5-methyl-3-pyrrolidinecarboxylic acid and (R)-3-pyrrolidinecarboxylic acid efficiently catalyzed the reactions of aldehydes with α-imino esters under mild conditions and afforded anti-Mannich products with high diastereo- and enantioselectivities (anti/syn up to 99:1, up to >99% ee). For the reactions of ketones with α-imino esters, (R)-3-pyrrolidinecarboxylic acid was an efficient catalyst (anti/syn up to >99:1, up to 99% ee). Evaluation of a series of pyrrolidine-based catalysts indicated that the acid group at the β-position of the pyrrolidine ring of the catalyst played an important role in forwarding the carbon−carbon bond formation and in directing anti-selectivity and enantioselectivity.

A practical organocatalytic strategy designed to mimic the l-rhamnulose 1-phosphate and D-fructose 1,6-diphosphate aldolases has been developed and shown to be effective in the preparation of carbohydrates and polyol derivatives. Threonine-based catalysts facilitated the aldol reaction of protected dihydroxyacetone or protected hydroxacetone with a variety of aldehydes to provide syn-aldol products with good yields and ee's up to 98%.

m-Diethynylbenzene macrocycles (DBMs), buta-1,3-diyne-bridged [4(n)]metacyclophanes, have been synthesized and their self-association behaviors in solution were investigated. Cyclic tetramers, hexamers, and octamers of DBMs having exo-annular octyl, hexadecyl, and 3,6,9-trioxadecyl ester groups were prepared by intermolecular oxidative coupling of dimer units or intramolecular cyclization of the corresponding open-chain oligomers. The aggregation properties were investigated by two methods, the (1)H NMR spectra and the vapor pressure osmometry (VPO). Although some discrepancies were observed between the association constants obtained from the two methods, the qualitative view was consistent with each other. The analysis of self-aggregation by VPO revealed unique aggregation behavior of DBMs in acetone and toluene, which was not elucidated by the NMR method. Namely, the association constants for infinite association are several times larger than the dimerization constant, suggesting that the aggregation is enhanced by the formation of dimers (a nucleation mechanism). In polar solvents, DBMs aggregate more strongly than in chloroform due to the solvophobic interactions between the macrocyclic framework and the solvents. Moreover, DBMs self-associate in aromatic solvents such as toluene and o-xylene more readily than in chloroform. In particular, the hexameric DBM having a large macrocyclic cavity exhibits extremely large association constants in aromatic solvents. By comparing the aggregation properties of DBMs with the corresponding acyclic oligomers, the effect of the macrocyclic structure on the aggregation propensity was clarified. Finally, it turned out that DBMs tend to aggregate more readily than the corresponding phenylacetylene macrocycles, acetylene-bridged [2(n)]metacyclophanes, owing to the withdrawal of the electron density from the aromatic rings by the butadiyne linkages which facilitates pi-pi stacking interactions.

Butadiyne-bridged [4 4 ]- and [4 8 ]metacyclophanes having exo -annular t -butyl groups were prepared by intermolecular Eglinton coupling of the dimeric unit or by intramolecular ring closure of the linear tetramer. Comparison of the 1 H and 13 C NMR spectra of [4 4 ]metacyclophane with those of [4 8 ]cyclophane and diphenylbutadiyne revealed its prominent geometrical feature due to deformation of the triple bonds from linearity. The [4 4 ]Metacyclophane was converted into [0 8 ]thiophenometacyclophane in good yield by treatment with sodium sulfide.

N -Tosylimidates acted as nucleophiles in highly enantioselective organocatalytic Michael addition reactions to α,β-unsaturated aldehydes in the presence of a catalytic amount of trialkylsilyl-protected diarylprolinol. In particular, α-phenyl-substituted N -tosylimidates showed good reactivity. We also demonstrate that the kinetic acidity of the α-proton of α-phenyl N -tosylimidate as measured by proton/deuterium NMR exchange experiments is correlated with the potential of N -tosylimidates to act as nucleophiles in organocatalytic reactions.

We synthesized diethynylbenzene macrocycles (DBMs), cyclic oligomers of diethynylbenzene, having functional groups in the periphery of the macrocyclic framework and investigated their self-association properties in solution resulting from π-π stacking interaction. The tetrakis-DBM having hexadecyl ester groups showed dimerization behavior not only in chloroform-d, but also in o-dichlorobenzene-d4.

[6](9,10)Anthracenophane (1a) was synthesized by the benzoannelation method starting from dibromo[6]paracyclophane 6 via diepoxyanthracenophanes 3a and 4a. In a similar fashion, peri-substituted de...

Extremely air- and acid-sensitive [6](9,10)anthracenophane (1), the smallest-9,10-bridged anthracene, has been synthesized by reductive deoxygenation of diepoxyanthracenophane (4) with a low-valent titanium reagent, and it was characterized by its NMR and electronic spectrum

[6](9,10)Anthracenophane (1a) was synthesized by the benzoannelation method starting from dibromo[6]paracyclophane 6 via diepoxyanthracenophanes 3a and 4a. In a similar fashion, peri-substituted de...

We synthesized diethynylbenzene macrocycles (DBMs), cyclic oligomers of diethynylbenzene, having functional groups in the periphery of the macrocyclic framework and investigated their self-association properties in solution resulting from π-π stacking interaction. The tetrakis-DBM having hexadecyl ester groups showed dimerization behavior not only in chloroform-d, but also in o-dichlorobenzene-d4.

A novel organocatalyst was developed that effectively catalyzed the reactions of unprotected or protected dihydroxyacetone with a variety of aldehydes to provide syn-aldol products with good yields and ee values up to >99%. Significantly, this amide catalyst was effective with a variety of nonaromatic aldehyde acceptors that had proven difficult in the presence of other catalysts. Reactions of protected dihydroxyacetone proceeded in aqueous media without addition of organic solvents.

The development of enantioselective anti-selective Mannich-type reactions of aldehydes and ketones with imines catalyzed by 3-pyrrolidinecarboxylic acid and related pyrrolidine derivatives is reported in detail. Both (3R,5R)-5-methyl-3-pyrrolidinecarboxylic acid and (R)-3-pyrrolidinecarboxylic acid efficiently catalyzed the reactions of aldehydes with alpha-imino esters under mild conditions and afforded anti-Mannich products with high diastereo- and enantioselectivities (anti/syn up to 99:1, up to99% ee). For the reactions of ketones with alpha-imino esters, (R)-3-pyrrolidinecarboxylic acid was an efficient catalyst (anti/syn up to99:1, up to 99% ee). Evaluation of a series of pyrrolidine-based catalysts indicated that the acid group at the beta-position of the pyrrolidine ring of the catalyst played an important role in forwarding the carbon-carbon bond formation and in directing anti-selectivity and enantioselectivity.

Catalytic enantioselective Michael addition reactions of α-amino functionalized aldehydes to nitroolefins have been developed. The Michael product was obtained in up to 98% ee, but the enantiomeric purity of the Michael product was decreased during isolation of the product.

Ein faszinierendes Assoziationsverhalten zeigt der starre Makrocyclus 1 in Losung. So reagiert er mit organischen Kationen zu ternaren Komplexen der Zusammensetzung (1⋅Kation)⋅1, und mit analogen Makrocyclen ohne Cyangruppen bildet 1 Heteroaggegate. R=CO2C8H17.

Intriguing association behavior in solution is exhibited by the rigid macrocycle 1. For instance, it reacts with organic cations to give ternary complexes of the composition (1⋅cation)⋅1, and with analogous macrocycles without cyano groups it forms heteroaggregates. R=CO2 C8 H17 .

Extremely air- and acid-sensitive [6](9,10)anthracenophane (1), the smallest-9,10-bridged anthracene, has been synthesized by reductive deoxygenation of diepoxyanthracenophane (4) with a low-valent titanium reagent, and it was characterized by its NMR and electronic spectrum

An automatic performance apparatus extracts characteristic data indicating individuality of performance of a player from performance data, compensates for score data exhibiting no individuality by the characteristic data, and executes an automatic performance using the compensated data. The apparatus includes a characteristic extraction unit and a characteristic regeneration unit. The characteristic extraction unit extracts characteristic data on the basis of a correlation between performance data and score data, and stores the extracted data in a characteristic data storage unit. The characteristic data is extracted with regard to styles of performance in association with notes, signs attached to the notes, dynamic marks, tempo marks, the general flow of music, and the like with reference to score data exhibiting no individuality. The characteristic regeneration unit compensates for arbitrary score data with the stored characteristic data to generate performance data. An electronic musical instrument is controlled based on the performance data, thereby obtaining automatic performance tones exhibiting the individuality of the player.

An electronic musical instrument capable of reporting a sound level and a tempo to be set. When a particular sound level or a particular tempo is selected and set, a click having a particular pitch matching the sound level or the tempo is generated to allow the user to recognize the sound level or the tempo on the basis of the pitch of the click. The instrument has a right and a left loudspeaker and, when the sound level is high or the tempo is fast, produces louder sound from one of the loudspeakers while, when the sound level is low or the tempo is slow, producing louder sound from the other loudspeaker.